Question

A ball is thrown at an angle of to the ground. If the ball lands 90 m away, what was the initial speed of the ball?

Answer 1

Answer:

The initial speed of the ball is 30 m/s.

Explanation:

It can be assumed that the ball is thrown at an angle of 45 degrees to the ground. The ball lands 90 m away. We need to find the initial speed of the ball. We know that the horizontal distance covered by the projectile is called its range. It is given by :

$R=\dfrac{u^2\ sin2\theta}{g}$

u is the initial speed of the ball.

$v=\sqrt{\dfrac{Rg}{sin2\theta}}$

$v=\sqrt{\dfrac{90\times 9.8}{sin2(45)}}$

v = 29.69 m/s

or

v = 30 m/s

So, the initial speed of the ball is 30 m/s. Hence, this is the required solution.